One of the most complex thing we’ve discovered in the universe is the Human Brain. And its complexity raises one fundamental question: What is reality?
For the past 20 years, I have been trying to understand how what happens in three pounds of Jell-O-like material somehow becomes us. What we feel, what matters to us, our beliefs and our hopes - everything we are happens in here.
David Eagleman Neuroscientist
I am David Eagleman, a writer and neuroscientist from the Stanford University School of medicine.
For me, there’s one mystery that is absolutely fundamental - what is reality? What if I told you that this world around us, this richly textured world, were all just an illusion constructed in your head?
For me, there’s one mystery that is absolutely fundamental - what is reality? What if I told you that this world around us, this richly textured world, were all just an illusion constructed in your head?
What if I said that the real world has no smell or taste? No sound? What if I said there’s no colour? If you could perceive reality as it really is out there, you wouldn’t recognise it at all. I want to show you how the brain takes in information, sifts through it to find patterns, and uses it to build the multi-sensory technicolour show that is your reality.
When I’m in the world my senses are flooded with sights and sounds and smells. It seems obvious that reality is just out there. There is a person, there is a cab. All I have to do is show up and my senses let me experience it all.
What is Reality
But there is a twist to this story. Let me show you something.
Take a look at this middle square here. Does that look more similar to the light square or the dark? Well, it looks like a light square, yeah? You might be surprised if I move it, now it look like a dark square.
Do you have a guess as to why there is an illusion here?
Observer “Well, it seems like there is a shadow, so it makes this darker.”
That is exactly right. Your brain is trying to understand the colours of things irrespective of the lighting and the shadows. So somehow it’s not about what’s hitting your eyes, it is about your brain’s interpretation.
Now, this is about more than just a visual illusion. It’s about a fact that’s central to our lives.
Our perception of reality has less to do with what’s happening out there and more to do with what’s happening in here.
To understand what’s going on, we first need to know how information from the world around us gets into the brain.
Understanding Reality
It feels as if sights and sounds just stream in through our eyes and our ears. But imagine if you could climb inside a human skull. When you step into the skull, you will find there is no way for light or sounds or smells to get directly in here.
This is a sealed chamber… so the brain sits in darkness and silence. It’s in total isolation. Your brain has never seen the outside world, but somehow you experience it. Now this might seem straightforward because we have portals to the outside world, like your eyes and ears, but these aren’t just piping in sights and sounds. Instead, photons of light or air compression waves, these are getting converted into the common currency of the brain - electrochemical signals.
Theses signals travel through dense networks of brain cells called neurons. There are 100 billion neurons in the human brain, and in every second of your life, each one of these is sending tens or hundreds of electrical pulses to thousands of other neurons. And somehow, all of this activity produces your sense of reality.
So whether it’s the bark of the dog or the smell of coffee or a view of a beautiful sunset, it’s all made of the same stuff in here. And this is the stuff of reality.
But how does the brain turn it into something meaningful? Well, it does it by sifting through the nonstop stream of incoming data to find patterns, which are then assembled into a reality. It’s an operation which is the product of millions of years of evolution. So efficient, so powerful that it’s work seems effortless and instantaneous.
Seeing is Believing
Take, as an example: sight.
The act of seeing feels so natural that it’s hard to appreciate the vast, sophisticated machinery running under the hood.
What is Brain Blindness when the Brain stops seeing, even when the eyes have vision
We often get our best view of how the brain operates when that operation is disrupted.
How a Disrupted Brain Operation can Change your View of the World
Combining all these streams of sensory data is an astonishing feat to pull off, but there’s one factor which really adds complication… timing.
Why our Sensory Data Information Timing is critical to Construct Our Perception
Sometimes it’s easy to assume that there is a single spot in the brain that takes care of this or that function - like an area for memory or generosity or empathy. But in fact, the vast networks of the brain are so much more complex than that.
Think of the brain like a city. If you were to look out over a city and ask, ‘Where is the economy located?’ you’d see that there’s no single answer to that. Instead the economy emerges as an interaction of all the elements.
So it is with reality. The raw materials of perception are gathered by our sensory receptors. They are turned into electrical signals and transported around our brains along a superhighway of neurons. Processed, they become our reality.
Some parts of Brain City specialise in vision, other districts care about hearing, some about touch, and so on.
Even within a sense like vision, you have streets that specialise in colours, or edges, or motions.
But, just like in a city… no neighbourhood operates in isolation. Instead the life of a city depends on the interaction between residents at all different scales. And somehow, out of all this interaction emerges your personal reality.
External Links
David Eagleman, Stanford University
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